That sounds reasonable, and Wade, a science reporter and editor for many years at Nature and the New York Times, seems an unimpeachable source. But many well-meaning people will regard his words as provocative and even dangerous.

For they fatally undermine the idea, widely shared by so-called progressives, that any apparent differences between groups of people are the product of nurture rather than nature, of social conditioning.

This has become dogma among certain social scientists. The American Anthropological Association states that race "is a recent human invention" and "is about culture, not biology." The American Sociological Association calls race "a social construct" and decries "the danger of contributing to the popular conception of race as biological."

Unfortunately for these folks, the decoding of the human genome in 2003 has led to research showing significant genetic differences among people descended from Africans, East Asians and Caucasians.

Those differences must have arisen from natural selection in the different environments they occupied from the time the first humans left east Africa.

They include not only skin pigment and facial physiognomy but many other physical characteristics, including genes that resist endemic diseases and (in Tibetans, developed only 3,000 years ago) the ability to live at very high altitudes.

Many of the progressives who reject the notion that races differ in significant respects are the same people who accuse those skeptical of global warming of ignoring science, even though the alarmists' warming models don't match the recent past or the present.

But at the same time they refuse to credit the much more soundly based science that Wade cites in detail.

These genomic-science skeptics fear that acknowledging differences between races will encourage people generally, and Americans in particular, to engage in racial discrimination.

That fear has some basis in history, as Wade concedes. But, as he argues, it has no relevance to life in America today.

Americans today are entirely capable of understanding that there is more difference within racial groups than between racial groups. This is a lesson they pick up from their families, at school, at work and in everyday life.

They know that some members of a racially or ethnically defined group that on average scores low on IQ tests will score far above average. They know that some members of a group that scores high on such tests will score far below average.

From that observation, ordinary Americans readily conclude that it is irrational to discriminate according to race or ethnicity or religion and that it is rational to judge individuals on their own merits.

Proof of this comes from our last two presidential elections. Most Americans know or can readily guess that blacks on average score below whites (and further below Asians) on intelligence tests.

But they also know — even his most vociferous critics don't deny this — that President Barack Obama, like all recent presidents and serious presidential candidates, is well above average in intelligence. They would not have elected him president, twice, if they thought otherwise.

So the fact that there are differences in average IQ scores, or in some other testable characteristic, between races does not undercut the case against group discrimination, at least for the large majority of Americans.

But it does undercut the case for racial quotas and preferences. It undercuts the case for the "disparate impact" legal doctrine that the Supreme Court concocted in a 1971 case on hiring discrimination.

The Court acted when memories were still fresh of resistance to racial desegregation orders in the South. But the doctrine is out of date 43 years later.

"Disparate impact" doctrine assumes that in a fair society we would find the same racial or ethnic or religious mix in every school, every occupation and every neighborhood. But that's nonsense, as anyone acquainted with American life knows.

Americans are quite capable of treating individuals fairly even while acknowledging group differences that, as science shows, are the result of recent, copious and regional natural evolution.

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